Correct descriptor shape for @JvmRecord annotated classes

This commit adds relevant functions: hashCode, toString, equals
(if the class is not a data class)
And supertype j.l.Record

It only affects descriptor contents, i.e. works for FE

^KT-43677 In Progress

core/descriptors/src/org/jetbrains/kotlin/resolve/AdditionalClassPartsProvider.kt

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.resolve
+
+import org.jetbrains.kotlin.container.DefaultImplementation
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.SimpleFunctionDescriptor
+import org.jetbrains.kotlin.incremental.components.LookupLocation
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.types.KotlinType
+
+@DefaultImplementation(impl = AdditionalClassPartsProvider.Default::class)
+interface AdditionalClassPartsProvider {
+    fun generateAdditionalMethods(
+        thisDescriptor: ClassDescriptor,
+        result: MutableCollection<SimpleFunctionDescriptor>,
+        name: Name,
+        location: LookupLocation,
+        fromSupertypes: Collection<SimpleFunctionDescriptor>
+    )
+
+    fun getAdditionalSupertypes(
+        thisDescriptor: ClassDescriptor,
+        existingSupertypes: List<KotlinType>
+    ): List<KotlinType>
+
+    object Default : AdditionalClassPartsProvider {
+        override fun generateAdditionalMethods(
+            thisDescriptor: ClassDescriptor,
+            result: MutableCollection<SimpleFunctionDescriptor>,
+            name: Name,
+            location: LookupLocation,
+            fromSupertypes: Collection<SimpleFunctionDescriptor>
+        ) {}
+
+        override fun getAdditionalSupertypes(
+            thisDescriptor: ClassDescriptor,
+            existingSupertypes: List<KotlinType>
+        ): List<KotlinType> = emptyList()
+    }
+}